The present invention relates to a method and a device for inspecting an active matrix substrate.
In inspection of an active matrix type liquid crystal display device, there may be a case where a liquid crystal display device is inspected after filling the space between an active matrix substrate and an opposite substrate with a liquid crystal (Japanese Patent Application Laid-open No. 5-288641 (FIGS. 1 to 5), for example). In this case, if a defect is found even in one pixel of the liquid crystal display device, the entire device becomes defective.
Therefore, a method and a device for inspecting a liquid crystal display device in the stage of an active matrix substrate have been proposed (Japanese Patent No. 3203864 (FIGS. 1, 3, and 4) and Japanese Patent No. 3191073 (FIG. 4)). In the active matrix substrate, a pixel select switching element and a capacitor are provided for each pixel. This method and device determine whether or not the pixel has a defect by detecting a current based on a charge stored in the capacitor.
However, according to the inventions disclosed in Japanese Patent No. 3203864 and Japanese Patent No. 3191073, if the detection timing varies for characteristics of the waveform of the inspection current based on the charge stored in the capacitor of each pixel, there may be a case where a normal pixel is erroneously determined to have a defect.